1. Field of Invention
The invention relates to fitness equipment and, in particular, to an elliptical exercise machine in accord with human factors engineering.
2. Related Art
The conventional elliptical machine design, as shown in FIG. 9, has a frame 91 whose front end extends upward with a vertical bar 92. Both sides of the vertical bar 92 are pivotally installed with two swing arms 93. The rear end of the frame 91 is mounted with a driving wheel 94. Both sides of the driving wheel 94 are disposed with a crank 95, respectively. Both sides of the frame 91 are installed with a stepping bar 96, respectively. The two stepping bars 96 are fixed with a stepping board 97, respectively. The two stepping bars 96 are pivotally connected to the ends of the two swing arms 93 by their front ends. The rear ends of the two stepping bars 96 are connected to the two cranks 95, respectively. The front end of the stepping bar 96 is dragged by the swing arm 93 to perform a reciprocal motion along an arc curve. The rear end of the stepping bar 96 is dragged by the crank 95 to move along a circular curve. Therefore, the stepping boards 97 on the two stepping bars 96 can move along an elliptical curve.
In order for the elliptical machine to fit users of different sizes, one often has to adjust the length of the crank 95, thereby satisfying the different footstep spans. However, the conventional elliptical machine design fixes the stepping boards 97 on the stepping bars 96, and the two stepping bars 96 are directly connected with the swing arms 93 and the crank 95. Therefore, the higher the steps and the larger the footstep span, the angle of the stepping boards during the exercise is also larger. This affects the comfort and the force exerted on the joints of the user. This is because the design does not fit human factors engineering.
Moreover, the conventional elliptical machine has elliptical curves. When the motion reaches the left and right extremities, the tangential speed has the largest change. Therefore, the user may experience frustration when the two stepping boards 97 move to the extremities of the elliptical curves.